Insulating Ductwork

Insulating HVAC ductwork can improve the system’s energy use efficiency by up to 20%. Uninsulated metal ducts lose a lot of warmth or cooling ability by the time the air reaches its destination. Especially if they travel long distances or through areas outside the home’s insulation envelope–like attics, unheated garages, and crawl spaces.

Insulating Ductwork

Why Insulate Ducts?

Insulating ductwork is usually not an essential job but the benefits are noticeable. Installing the insulation is an inexpensive DIY project, and it continues to show payback in comfort and money saved for years.

Saves Energy

Uninsulated ductwork loses up to 20% of the heating or cooling ability of the air passing through the ducts. Insulating the ducts eliminates leaks and keeps the air inside closer to its optimum temperature The HVAC motor runs less. And you save on energy costs.

Eliminates Condensation

Cool air passing through ducting in warm parts of the house can cause condensation inside the ducting and on the outside of the pipes. Mold and mildew will actually grow inside the duct where moisture is present; and then be blown throughout the house. Duct insulation prevents warm air from coming in contact with the ductwork and eliminates mold and mildew growth.

Reduces Noise

Metal ducts make noise in three ways. Air traveling through the pipes. Clicking of expansion and contraction; worst case–banging on the floor or supports. Blower motor. All can be heard at each vent location. Insulating ductwork reduces all of these noises.

Where To Insulate Ductwork

Any ductwork passing through unheated spaces–like attics, crawl spaces, or unheated basements–definitely requires insulation. These ducts are the most vulnerable to energy loss and condensation.

Consider insulating all remaining ductwork at the same time. Adding insulation to them may not be as essential, but insulating all of the ducting will add to comfort and quiet.

Most flexible ducting is factory-insulated and requires no further insulation.

Types Of Ductwork Insulation

The two most common types of duct insulation are foil-faced fiberglass and reflective polyethylene-encased air bubbles sandwiched between radiant barriers. Most types of ductwork insulation are available from home improvement outlets and online.

Fiberglass Ductwork Insulation

Foil-faced fiberglass is the most common type of duct insulation. It is available in R-values up to R-12.0. The flexible product comes in rolls of various lengths and widths and wraps around pipes. Rigid boards can be cut to fit rectangular ducting.

  • Inexpensive.
  • Easy to Install.
  • Replaceable. Easy to remove and replace if necessary.
  • Absorbs Noise.
  • Moisture. May absorb moisture which reduces the R-value.

Reflective Ductwork Insulation

Reflective air bubble duct insulation is stable, lightweight, and easy to install. One of the most popular products is manufactured by Reflectix Inc. It has an R-value of up to R-6.0.

  • Lightweight.
  • Easy to Install.
  • Inexpensive.
  • Little Waste.
  • Moisture. Will not absorb moisture.
  • Noise. Not good at absorbing noise.

Cost of Ductwork Insulation

Ductwork insulation costs vary. They are dependent on types of material, R-values, and availability. Here are a few average costs.

  • Duct Board. Approximately $1.50 per square foot. Foil-faced fiberglass or mineral wool.
  • Duct Wrap. Approximately $1.00 per square foot. Foil-faced fiberglass.
  • Reflective Wrap. Approximately $0.85 per square foot.
  • Contractor. Approximately $2.50 per square foot supplied and installed.